Part 1. The Field of the Invention.
This invention relates to novel improved caps for writing instruments. More precisely, the invention relates to caps for writing instruments which can provide a substantially air-tight seal about the nib or point carried by the barrel of instrument and which also provides means to permit air to flow through the cap.
Part 2. Description of the Prior Art.
Caps for writing instruments such as markers or pens are well known to the art. Essentially, such caps are designed to provide a substantially air-tight seal about the nib or point of the instrument to prevent dry-out and also to protect the nib or point from physical damage. Unfortunately, a writing instrument cap designed to provide an air-tight seal can also present a potential threat to safety since the cap can block passage of air if swallowed. The industry has been actively engaged in programs designed to develop caps which would eliminate or at least minimize this potential safety threat. For example, caps which include a clip protruding outwardly along a major portion of the cap surface length are believed to reduce the threat since the protruding clip may provide a passageway for air. Also, U.K. Patent 2,174,374 discloses a cap which includes ribs which provide passageways arranged about the exterior of the cap. However, despite such developments, the need remains for caps which can be produced in high volumes at relatively low costs and have the combined capability to provide an air-tight seal about the point or nib and also permit passage of air through internal regions of the cap.